XII. "The Behaviour of Measuring-Rods and Clocks in Motion"
"The rigid rod is...shorter when in motion than when at rest, and the more quickly it is moving, the shorter is the rod" (42-3). For the observer on the embankment, the rod in motion on the train is moving as he is measuring it, such that the end on the left (assuming the train is moving to his right) moves closer to the end on the right as he measures. But I still don't entirely understand why time has to be factored in here...
"...in the theory of relativity the velocity c plays the part of a limiting velocity, which can neither be reached nor exceeded by any real body" (43). Matter, in other words, can never travel as fast as light.
"As a consequence of its motion the clock goes more slowly than when at rest" (44). I understand these conclusions, but not entirely how he arrived at them (because I don't understand math). Why, in even more simplistic terms, are length and time relative in this way?
XIII. "Theorem of the Addition of Velocities: The Experiment of Fizeau"
???
XIV. "The Heuristic Value of the Theory of Relativity"
- LORENTZ/galilei
Again, the principle of relativity AND the constant c are entirely compatible.
*Is Einstein saying that laws hold relative to the system, i.e., that the same laws govern each system, but not both together--that while the same laws hold within each system of co-ordinates, no laws can govern the macrosystem which includes both K and K'??
XV. "General Results of the Theory"
*Einstein's primary goal, really, is to simplify, unify, and reduce multiplicity--to domesticate Being in/and the world (52).
In practice, the effects of velocity on measurements are too negligible to be of any use (these velocities are too diminutive compared to c). Atomic motion, however, is rapid enough that these calculations have enormous ramifications (52-53).
Conservation laws (of mass and energy) were previously thought separate. Relativity proves their unification/inseparability (54). This goes along with Everett and the two-slit experiment, in which mass behaves as both matter AND energy: "the inertial mass of a body is not a constant, but varies according to the change in the energy of the body" (55). These laws, then, become "identical." But how, exactly??
Again, this has never been important to classical physicists because its effects are too small to be noticed on the macro level. Atomically, though, it becomes crucial, as we see later with Everett and his many-worlds conjecture.
56-57: "instantaneous actions at a distance" - Huh??
XVI. "Experience and the Special Theory of Relativity"
Electromagnetics and the study of "fixed stars" confirms the Maxwell/Lorentz propositions and the theory of relativity (58-59). I still don't understand, though, exactly what Maxwell and Lorentz said/did.
Beta-rays consisting of negatively electrified particles (electrons) moving at high velocities: Common sense would say that electrons should be going willy-nilly as a result of their own repellent forces--the nature of like charges to repel one another. And yet they are held in orbit. Ergo, there must be "forces of another kind operating between them" (60). This is posited as gravity.
62- aether-drift (???) (62-64)?
XVII. "Minkowski's Four-dimensional Space"
We live in a 4-D space-time continuum (65): SPACE=3D (x,y,z); TIME=1D (t). Physicists previously had treated time as "independent" and "absolute" (66). But relativity shows that this is not the case: "the time co-ordinate plays exactly the same role as the three space co-ordinates" (67).
All of this is hotly contested, of course, at least in the humanities. We often insist that time is "made up," fictive and abstract in a way the physical world (SPACE) is "real" and tangible. But what if this isn't true? What if spacetime exists, and not only exists, but "bends"? How can we conceive of this in a field that has assumed time as a singular abstraction, autonomous at best and fictive at worst?
There is also the fact that relativity, as Einstein conceives of it, is a "purely formal addition to our knowledge" (68). He says that "the natural laws satisfying the demands of the (special) theory of relativity assume mathematical forms" (67). Indeed, his entire theory is mathematically conceived, numerically constructed. Disciples of Foucault and Derrida may consider this highly suspect, as it is (despite mathematicians' protests, and claims to objectivity) a kind of signification system which is inherently and fundamentally detached from that which it is meant/assumed to signify. That being said, is overdetermining this constructedness any less ridiculous/unnecessary/counterproductive than overdetermining linguistic constructions? Can't we discuss these principles seriously and still acknowledge the limitations of the system (as the poststructuralists indeed do)? It seems to me that we can "accept" these constructions, as we do language, as a system of practical utility and not one of absolute "truth." Are Einstein's mathematically derived assertions any less "real" than the assertions of, say, Derrida, simply because they don't ceaselessly fetishize their own constructedness? Einstein does, after all, begin his book with a fairly full-throated acknowledgment of the tenuousness of his system of signification (very much in the spirit of Saussure).
